Architectural concrete rubbing machine



United States Patent M 3,327,433 ARCHITECTURAL CONCRETE RUBBING 2 Claims. (Cl. 51--283) This invention relates to an architectural rubbing machine for producing an architectural finish on concrete or similar materials.

This application is a continuation-in-part of US. patent application Ser. No. 200,377 filed June 6, 196-2, and now abandoned.

In the use of concrete for walls, piers and other structures, the concrete is generally poured into a form of the desired configuration. When the boards or other structure making up the mold are removed from the hardened concrete, the exposed surfaces of the concrete generally have surface irregularities, such as voids or pores which are rough and unattractive. If the concrete is to be covered with bricks or stone, the rough unfinished concrete surfaces are normally not objectionable, but when the concrete is to be left exposed, particularly in connection with an otherwise attractive building, the concrete surfaces must be provided with an architectural concrete finish which is smooth and attractive.

Heretofore, such architectural concrete finish has been obtained by hand rubbing the concrete with a flat long Carborundum stone, after the concrete has been wet with water by brush or spray. Mortar, a mixture of cement, sand and water, has sometimes been used to fill in the holes or voids in the concrete surfaces. Thereafter, the surface has been brushed with a moist brush or passed over with a cork or rubber float, producing a smooth uniform finish.

Such prior art procedure has'been tedious and time consuming especially on large concrete columns, walls, floor slabs, and other similar large surface areas. Efforts have been made to do such work with high speed grinders, but such grinding does not produce the desired architectural concrete finish.

An object of this invention is to provide an architectural concrete rubbing machine for producing an architectural finish on concrete surfaces and the like.

An important object of this invention is to provide a new and improved architectural concrete rubbing machine for concrete surfaces and the like wherein such rubbing machine has an annular rubbing stone with a central recess for receiving mortar so that such mortar is dis.- tributed between the rubbing face of the annular rubbing stone and the concrete to fill in the voids, pores and other imperfections in the concrete surface.

A further object of this invention is to provide a new and improved architectural concrete rubbing machine which has an annular rubbing stone which is rotated by a fluid-driven motor at relatively slow speeds so that mortar may be fed to the rubbing face of the stone in the proper amounts for producing an architectural finish on the concrete and the like.

A particular object of this invention is to provide a lightweight rubbing machine which an operator holds in his hands in use and which has a hose filled with oil or other fluid connected thereto for supplying power, so that the operator may safely and easily move about without being endangered by electrical lines, belts, chains, flexible shafts, or other obstacles when so moving to architecturally finish concrete or the like.

The preferred embodiment of this invention will be described hereinafter, together with other features there- 3,327,433 Patented June 27, 1967 of, and additional objects will become evident from such description.

The preferred embodiment of this invention will be described hereinafter, together with other features thereof, and additional objects will become evident from such description.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forminga part thereof, wherein an example of the invention is shown, and wherein:

- FIG. 1 is a view, partly in elevation and partly in section, of the apparatus of this invention in position for use on concrete or the like;

FIG. 2 is a view taken on line 22 of FIG. 1 and further illustrates the invention.

In the drawings, the letter A designates generally a rubbing stone which is powered by a hydraulic motor B or other source of fluid power for rotating the stone A at a relatively slow speed, for a purpose to be hereinafter described. The rubbing face 10- of the stone A is adapted to be placed in contact with a concrete member C which may be a concrete wall, column or other surface, whether formed of concrete, cinder blocks, building stones, or a similar material. The rubbing stone A is of a light weight construction and is annular to provide a recess R for receiving mortar G which is distributed between the face 10 and the surface of the member C at a slow speed to obtain an architectural concrete finish. The stone A is preferably eccentrically mounted so as to provide a more effective rubbing action.

Considering the invention more in detail, the annular rubbing stone A is preferably made of a light weight material which includes silicon carbide grit or particles which are bonded together with a suitable bonding agent such as vitrified clay. The bonding agent should be of medium hardness, and the silicon carbide particles or grit should preferably be of such size that the majority passes a forty-six mesh standard screen. Other materials may be used, but the foregoing material for the rubbing stone A is preferred due to its light weight and its effective rubbing action.

The rubbing stone A is preferably bonded to a steel plate 12 with a suitable adhesive such as an epoxy resin. In normal use, the plate 12 is circular in shape and has a 'diameter corresponding to the outer diameter of the annular stone A. A plurality of openings or holes 12a are prefer-ably provided in the plate 12 for receiving a corresponding number of bolts 14.

The hydraulic or fluid-driven motor B has a shaft 15 extending therefrom which is rotated by such motor B.

The shaft 15 preferably has a flange 16 formed at its outer end. Such flange 16 has a plurality of holes therethrough for receiving the bolts 14. The bolts 14 are provided with nuts 14a which are threaded thereon for holding the plate 12 securely to the flange 16. In that manner, the stone A is secured to the motor B so that it may be removed for replacement or repair. It will be appreciated that other means for connecting the annular stone A to the motor B may be employed, if desired.

It should be noted that the center axis 15a of the shaft 15 is offset from the central axis 12b of the plate 12 and the corresponding central axis of the annular stone A. By reason of such offset, the stone A is adapted to rotate eccentrically which results in an overlapping rubbing action.

The motor B is of any suitable construction and is provided with oil or hydraulic fluid by means of a pump 20 which is connected to a fluid reservoir 21 through a connecting pipe or tube 22. The pump 20 discharges the fluid through a flexible supply line 24 to the fluid-driven motor -B. Preferably, such flow line 24 extends through a handle 30 which is directly connected to the motor B. Such handle 30 has a valve 31 mounted therewith and connected in the supply line 24 for controlling the flow of the fluid to the inlet end 24a of the motor B.

The motor 20 is driven by a gasoline engine 35 or any other suitable source of power. Preferably, the gasoline engine 35, the pump 20 and the reservoir 21 are mounted on a common base or vehicle. It is to be note-d that the fluid from the motor B returns to the reservoir 21 through a return line 36 which has a connection through line 36a to the valve 31.

The valve 31 is schematically illustrated in FIG. 2 and may be any standard three-way valve which is adapted to permit flow through the line 24 and the inlet 24a to the motor B through the valve flow portion 31a. The side flow portion 31b is closed off during such flow to the motor B from the line 24.. However, when it is desired to stop the motor 'B, the valve 31 may be rotated in the usual manner to position the flow opening 31a in alignment with the connecting tube 36a and the flow opening 31b in line with the bottom portion of. the supply line 24. In that way, the fluid flowing from the supply line 24 is bypassed through the valve 31 and returns through the line 36a and the return line 36 to the reservoir 21 without reaching the motor B. Such valve 31 is readily accessible to the operator so that he may thereby control the rotation of thestone A by simply controlling the valve 31.

For ease in handling the apparatus of this invention, an additional handle 40 is secured to the motor B at its flange 39 by means of a retaining screw 41 or any other suitable attaching means. For must uses, the handle 40 is spaced approximately 60 from the handle 30 as indicated in FIG. 2, although such spacing may vary for diflerent conditions.

In the operation or use of the apparatus of this invention, the engine 35 is started so as to operate the pump 20 through the driving of the shaft 35a connecting the engine 35 to the pump 20. The pump 20 develops and circulates the fluid under pressure from the reservoir 21 through the supply line 24. Initially, the valve 31 is in the bypass position so that the fluid does not reach the motor B.

The mortar G which is of the usual mixture of cement, sand and water is placed in the recess R and then the stone A is placed with its face in proximity to the article C of concrete or the like for the rubbing operation. The valve 31 is then shifted to the flow position indicated in FIG. 2 so that the fluid reaches the motor B and rotates same. Such rotation of the motor B imparts rotation to the shaft and the stone A.

In the usual instance, the motor B rotates at about 200 to about 350 r.p.m., which is relatively slow so that the mortar G is fed or distributed onto the entire annular surface 10 of the stone A without excessively throwing such mortar by centrifugal force. Thus, the mortar G is fed at the desired rate between the face 10 and the concrete C so that a proper amount of the mortar is present on the face 10.

When it is desired to stop the rotation of the stoneA, the valve 31 is rotated to the bypass position so that the fluid no longer flows to the motor B.

Due to the light weight of the apparatus of this invention, and the handle construction as illustrated in FIG. 2, the apparatus is easy for one man to handle. Additionally, because of the proper feeding of the mortar G from the central recess R with the relatively slow speed motor, an effective rubbing in and floating of the mortar on the concrete is obtained to thereby fill the Voids or holes and otherwise provide an architectural concrete finish. Other advantages of the present invention Will also appear to those skilled in the art.

It should be noted that the return line 36 is shown as separate from the handle 30, but in actual practice, such line 36 would preferably pass through the handle 30 in the same manner as the supply line 24. In that way, both of the lines 24 and 36 may be kept from interfering with the convenient operation of the apparatus.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

1. A method of rubbing concrete, comprising the steps of:

(a) disposing mortar in an internal recess of an annular rubbing stone having an annular rubbing face for.

rubbing contact with concrete, and

(b) rotating said rubbing stone at a speed to gradually feed the mortar from the recess onto the rubbing face during rotation of the rubbing stone for filling voids and pores in the concrete to smooth the concrete surface for providing an architectural finish. 2. The method set forth in claim 1, wherein the rubbing stone is rotated at a speed below about 350 rpm.

References Cited UNITED STATES PATENTS ROBERT C. RIORDON, Primary Examiner.

L. S. SELMAN, D. G. KELLY, Assistant Examiners. 

